Metyrapone Test

The metyrapone test evaluates how the adrenal glands respond to
adrenocorticotrophic hormone, or ACTH.
ACTH is made in the pituitary gland and travels through the bloodstream to the
adrenal glands. There it triggers the release of another hormone called
cortisol.

Cortisol affects the breakdown and use of fats, carbohydrates,
sodium, potassium, and protein.
In this test, the medication metyrapone is given to a person to evaluate the ability
of the adrenal gland to make cortisol.

Who is a candidate for the test?

The metyrapone test may be done if a problem is suspected in a person's:

adrenal gland, such as a tumor or other factor that keeps the gland from
working correctly

pituitary gland

How is the test performed?

Metyrapone is given in 4 doses over a 24-hour period, or
sometimes as a single dose at 11 p.m. Metyrapone is given orally in tablet
form. At 8 a.m., a blood sample is taken from a vein on the forearm or hand.

First, the skin over the vein is cleaned with an antiseptic. Next, a strong
rubber tube, or tourniquet, is wrapped around the upper arm. This enlarges the veins in the lower arm by restricting blood flow. A fine needle is gently inserted into a vein and the tourniquet is removed. Blood flows from the vein through the needle. It is collected in a syringe or vial. After the needle is withdrawn, the puncture site is covered to prevent bleeding .
The blood sample is sent to a lab. There, cortisol and ACTH in the blood sample are measured.